class Reline::LineEditor

def render_partial(prompt, prompt_width, line_to_render, this_started_from, with_control: true)
_lines, height = split_by_width(line_to_render.nil? ? prompt : prompt + line_to_render, @screen_size.last)
_up_from_last_line = 0
roll_partial_screen
_visual_line = this_started_from + (height - 1)
_screen_line = @scroll_partial_screen + (@screen_height - 1)
@scroll_partial_screen - this_started_from) >= height
Render nothing because this line is before the screen.
sual_lines = []
f this_started_from > last_screen_line
Render nothing because this line is after the screen.
sual_lines = []

leted_lines_before_screen = []
 @scroll_partial_screen > this_started_from and last_visual_line >= @scroll_partial_screen
# A part of visual lines are before the screen.
deleted_lines_before_screen = visual_lines.shift((@scroll_partial_screen - this_started_from) * 2)
deleted_lines_before_screen.compact!
d
 this_started_from <= last_screen_line and last_screen_line < last_visual_line
# A part of visual lines are after the screen.
visual_lines.pop((last_visual_line - last_screen_line) * 2)
d
ve_cursor_up(deleted_lines_before_screen.size - @started_from)
rsor_up_from_last_line = @started_from - deleted_lines_before_screen.size
h_control
eight > @highest_in_this
ff = height - @highest_in_this
roll_down(diff)
ighest_in_all += diff
ighest_in_this = height
ve_cursor_up(diff)
f height < @highest_in_this
ff = @highest_in_this - height
ighest_in_all -= diff
ighest_in_this = height
_cursor_up(@started_from)
rted_from = calculate_height_by_width(prompt_width + @cursor) - 1
or_up_from_last_line = height - 1 - @started_from
ine::Unicode::CSI_REGEXP.match?(prompt + line_to_render)
put.write "\e[0m" # clear character decorations
_lines.each_with_index do |line, index|
ne::IOGate.move_cursor_column(0)
ine.nil?
 calculate_width(visual_lines[index - 1], true) == Reline::IOGate.get_screen_size.last
# reaches the end of line
if Reline::IOGate.win? and Reline::IOGate.win_legacy_console?
  # A newline is automatically inserted if a character is rendered at
  # eol on command prompt.
else
  # When the cursor is at the end of the line and erases characters
  # after the cursor, some terminals delete the character at the
  # cursor position.
  move_cursor_down(1)
  Reline::IOGate.move_cursor_column(0)
end
se
Reline::IOGate.erase_after_cursor
move_cursor_down(1)
Reline::IOGate.move_cursor_column(0)
d
xt
put.write line
eline::IOGate.win? and Reline::IOGate.win_legacy_console? and calculate_width(line, true) == Reline::IOGate.get_screen_size.last
A newline is automatically inserted if a character is rendered at eol on command prompt.
est_height -= 1 if @rest_height > 0
put.flush
first_prompt
irst_prompt = false
re_input_hook&.call
 visual_lines.empty?
ne::IOGate.erase_after_cursor
ne::IOGate.move_cursor_column(0)
h_control
st after rendring, so the cursor is on the last line.
inished?
line::IOGate.move_cursor_column(0)

Moves up from bottom of lines to the cursor position.
ve_cursor_up(cursor_up_from_last_line)
This logic is buggy if a fullwidth char is wrapped because there is only one halfwidth at end of a line.
line::IOGate.move_cursor_column((prompt_width + @cursor) % @screen_size.last)